The present invention relates in general to water circulation systems for potable water storage tanks and more particularly, to an apparatus for use with single pipe water storage tanks which minimizes thermostratifying and further promotes water circulation with a positive retention time.
With many conventional potable water storage tanks as used in a typical city or county water supply, a single pipe is used to fill and drain the water within. Typically, this single pipe injects and removes water from the base of the storage tank. In such a system, the water which enters the tank is usually the water which exits immediately thereafter when a supply of water is needed by the community. This means that there is little if any retention time for water which is injected into the tank. This is especially true in warmer months when the water which enters is often colder than the water within the tank and therefore tends to remain at the lowest portion of the tank. Thus, water which is removed is typically the same water which immediately theretofore entered. This form of water removal precludes thorough mixing with or depletion of water which was at the upper portions of the storage tank. Without a through mixing of inlet and outlet water, the tank tends to thermostratify. This means that the water has a temperature gradient within the tank. The colder portions of said gradient tend to induce sweating on the outside of said storage tank and thereby cause said tank to externally deteriorate. That is, since the tanks are typically manufactured of an external ferrous metal material, said material oxidizes or its exterior coating deteriorates due to the sweated moisture present on its exterior surface. Furthermore, in chlorinated water supply systems, the lack of thorough mixing within a single pipe system denies any injected chlorine the time to circulate and mix with the water within the storage tank. This may cause excessively low or high concentrations of chlorine in the municipal water supply.
In the colder months, ice will typically form on the top surface of the water held in a storage tank. The greater the ice buildup, the greater the potential for damage to the interior protective coating of the storage tank. Thus, a city or county water supplier has a vested interest in minimizing surface ice buildup. In the winter months, water which enters the tank from the base is typically warmer than the surrounding water. Unfortunately, with a conventional single pipe system, the inlet water is unable to reach the top surface of the storage water without diffusing and cooling with the water stored within the tank. Thus, the potential for inlet water minimizing surface freezing within the tank is not utilized.
Prior to the art of the present invention, the only solution for solving the thermostratification problem in a single pipe system has been the incorporation of a separate inlet and outlet pipes. That is, the inlet pipe functions only as a conduit for inlet water and a second pipe of sufficient fire flow diameter is added to provide outlet flow at the base of the water storage tank. This modification is quite costly and time consuming.
Accordingly, it is an object of the present invention to provide an apparatus for positive water retention and circulation in storage tanks which injects inlet water at a higher level within the storage tank and removes water from a lower level within the tank thereby promoting a positive retention time of injected water.
Another object of the present invention is to provide an apparatus for positive water retention and circulation in storage tanks which is easily adaptable to a conventional single pipe potable water storage tank.
A further object of the present invention is to provide an apparatus for positive water retention and circulation in storage tanks which minimizes thermostratification within the storage tank and also provides for a thorough mixing of inlet and outlet water.
A still further object of the present invention is to provide an apparatus for positive water retention and circulation in storage tanks which is able to minimize ice buildup on the surface of the stored water during winter months.